It begins the third era of spacecraft for NASA's space network for routing communications from the International Space Station, transmitting science data from orbiting satellites and tracking booster rockets.

The system began taking shape in 1983, replacing the smattering of ground stations around the world that provided periodic contact with orbiting spacecraft. Over the past three decades, however, TDRS created a constellation of geosynchronous satellites 22,300 miles above Earth for constant communications.

From such a high vantage point, TDRS satellites look down on the entire globe, receiving transmissions from fast-moving craft flying only a few hundred miles in altitude and channeling those signals to dedicated terminals for dissemination to mission controllers.

To keep the infrastructure maintained, NASA is preparing to launch TDRS K, plus sister-satellites TDRS L in 2014 and TDRS M in 2015. Together, they will ensure the constellation's viability well into the next decade.

"We've got to make sure we continue to provide the services a whole host of users come to rely on," Jeff Gramling, NASA's TDRS project manager.

After deploying the first generation of craft aboard space shuttle missions through 1995, a second batch flew on Atlas 2A rockets between 2000 and 2002. Now, NASA has bought this latest trio using mostly the same specs as the last birds, albeit with updated components.

TDRS K was shipped to the Cape from Boeing's manufacturing factory on Dec. 18. It underwent final electrical checkouts, the loading of its maneuvering propellant and encapsulation in the rocket's 14-foot-diameter aluminum nose cone.

In the wee hours Sunday morning, the spacecraft departed nearby Titusville where it had undergone pre-flight processing at the commercial Astrotech facilities and headed for the spaceport around 2:15 a.m.

Traveling across 405 in a slow-moving convoy, the payload turned northward to pass through Kennedy Space Center, going by the Vehicle Assembly Building and the old space shuttle launch pad before cruising down along the beach to the Atlas rocket's Vertical Integration Facility.

After pulling up to the doorway of the 30-story-tall VIF where the Atlas rocket was assembled and tested this month, technicians went to work attaching the heavy-duty lifting sling to hoist the spacecraft in the bullet-shaped fairing off the ground and atop the Centaur upper stage. The initial phase of attachment was completed at 10:40 a.m.

The combined systems test between TDRS K and the Atlas vehicle will occur in the coming days to verify the payload and rocket are talking to each other properly, followed by final closeouts of the vehicle for flight.

Mission managers will gather for the Launch Readiness Review at 6:30 a.m. next Monday to assess the progress of work and any issues before giving concurrence for rollout to the pad later the same morning, around 10 a.m.

The United Launch Alliance-made, two-stage rocket was stacked aboard a mobile launching platform that will wheel the fully-assembled vehicle out to the launch pad one-third-of-a-mile away.

The Atlas 5 system at the Cape is meant to spend minimal time on the "clean pad" at Complex 41, which has no gantry.

The launch countdown picks up just before 2 p.m. on Tuesday afternoon, leading to fueling operations starting at 7 p.m.